Path: utzoo!attcan!uunet!ns-mx!jay.weeg.uiowa.edu!jnford
From: jnford@jay.weeg.uiowa.edu (Jay Ford)
Newsgroups: comp.windows.x
Subject: Re: xterm cut and paste
Keywords: blank truncation
Message-ID: <1997@ns-mx.uiowa.edu>
Date: 30 Jul 90 19:44:37 GMT
References: <90Jul27.024537edt.446@smoke.cs.toronto.edu>
Sender: news@ns-mx.uiowa.edu
Reply-To: jnford@jay.weeg.uiowa.edu (Jay Ford)
Organization: Weeg Computing Center, University of Iowa, Iowa City, IA, USA
Lines: 70


In article <90Jul27.024537edt.446@smoke.cs.toronto.edu>,
moraes@cs.toronto.edu (Mark Moraes) writes:
|> 
|> Jim Fulton fixed at least one bug in my fix -- enclosed.  Please apply
|> this as well as the one in the referenced article, otherwise there are
|> likely to be garbage characters, (usually NULs at the end of the cut
|> text)
|> 
	[patch deleted]

That patch did get rid of the NULs, but there is another problem.

Blanks at the end of a line get incorrectly truncated when the line is not the
last one in the cut region.  That is, the line with the trailing blanks is
followed by other lines, and all the lines are to be cut as one wrapped line.

Here is the behavior I see, where the line in question is not the last line.

condition				result
---------				------
1. no blanks at end of line		lines are cut correctly, as one line

2. one blank at end of line		the lines are cut as one line, but the
					single trailing blank is removed

3. multiple blanks at end of line	the blanks are truncated, and the cut
					contains a NL at the end of this line

Perhaps some examples would help.  Assume a window width of 20 columns.

Condition 1:
	         1         2
	12345678901234567890
	% echo abcdefghijklm
	nop

	resulting cut region is:
		echo abcdefghijklmnop

Condition 2:
	         1         2
	12345678901234567890
	% echo abcdefghijkl
	nop

	resulting cut region is:
		echo abcdefghijklnop
	(blank is missing after l)

Condition 3:
	         1         2
	12345678901234567890
	% echo abcdefghijk
	nop

	resulting cut region is:
		echo abcdefghijk
		nop
	(newline after k)


From glancing at the xterm code (button.c) it seems that the blank truncation
might be hard to work around.  The LastTextCol and Length functions ignore
trailing blanks, so anything which uses those functions will not get the blanks
counted in the line length.


Jay Ford,  Weeg Computing Center,  University of Iowa,  Iowa City,  IA  52242
jnford@jay.weeg.uiowa.edu  or  jnfordpb@uiamvs.bitnet,  319-335-5555